As computer display systems have increased in resolution, target acquisition has also become increasingly more difficult. Target acquisition refers to accessing an on-screen target, typically an iconic representation of some item displayed on the display device, using a pointer or another object/icon. The pointer may be manipulated directly, such as using a stylus on a pen-based tablet computer, or indirectly, such as using a mouse on a typical desktop computer.
Because modern display systems have very fine resolution, they are able to display substantial information in a relatively small area. The result of the larger display resolution is that a user must be very accurate to acquire/access any particular item on the display system. Unfortunately, target acquisition expands beyond a simple point and click operation to a continual directional correction process, especially over large distances.
At least one solution directed to facilitating target acquisition has been set forth by Michael McGuffin, et al., Acquisition of Expanding Targets, ACM Conference on Human Factors in Computing Systems (CHI), 2002, pp. 57-64. In his article, Mr. McGuffin proposes expanding the displayed size of a target as a function of the distance between the pointer and the target. FIGS. 1A and 1B are pictorial diagrams of displayed content 100 on a display system for illustrating the techniques described by Mr. McGuffin in expanding targets as the pointer approaches them.
With regard to FIG. 1A, the displayed content 100 includes various targets, including targets 102-106, all in their normal, i.e., unexpanded, displayed state. Additionally, a user is moving pointer 120 towards target C 102. However, because the distance between pointer 120 and any of the targets exceeds some predetermined threshold, the targets remain unexpanded.
FIG. 1B illustrates the same displayed content 100 as the pointer 120 crosses various threshold distances between it and the targets. For example, target E 106 is closest to the pointer 120, and accordingly is expanded to the largest expansion size for target acquisition. Target D 104 is also quite close and is expanded accordingly, though not to the same extent as target E 106. Similarly, target C is slightly expanded as the pointer 120 is within a particular threshold for its expansion.
As can be seen in FIG. 1B, as targets are temporarily expanded to facilitate their acquisition, the surrounding area is affected. As can be seen between FIGS. 1A and 1B, several surrounding targets, such as targets 108-116, have been forced to temporarily move from the actual, unexpanded location. This has the pernicious side-effect of making it somewhat more difficult to acquire targets when they are proximately located to each other. Thus, if the intent of the user in FIG. 1A was to acquire target C 102, then moving the pointer 120 within target E 106 and target D 104 made it more difficult as target C has been shifted to the left. In other words, as the pointer 120 crosses targets to reach the intended target, the intended target moves. Clearly, this manner of expanding targets does not always facilitate target acquisition.
In light of the above identified issues, what is needed is an improved system and method for facilitating target acquisition. The present invention addresses this and other issues found in the prior art.